1. Field of the Invention
The present invention relates to a technical field of heat exchangers, and particularly, to an adjustable refrigerant distribution device and a heat exchanger having same.
2. Description of the Related Art
In a refrigerant circulation process, an overcooled refrigerant from a condenser is depressurized via a throttling device to an evaporation pressure and an evaporation temperature, and then enters an evaporator. The refrigerant becomes a gas-liquid two-phase refrigerant after adiabatic throttling, and the vapor content makes up about 10% to 30% of the total mass of the refrigerant. For the gas-liquid two-phase refrigerant, due to differences between liquid and gas in density, viscosity and other physical properties, the inertia and gravity have different degrees of influences on the liquid refrigerant and the gas refrigerant, and hence the refrigerant may encounter a gas-liquid stratification phenomenon after entering a heat exchanger, like a parallel flow heat exchanger (a microchannel heat exchanger), which leads to an uneven refrigerant distribution in flat tubes—dry evaporation occurring in a part of the flat tubes but too much liquid supplied in another part of the flat tubes, thus degrading a heat exchange performance of the heat exchanger.
In the prior art, it has been proposed to insert a refrigerant distribution pipe into a header, so that the refrigerant enters the header through a distribution hole in the refrigerant distribution pipe and hence is distributed to the flat tubes. However, some defects still exist in the refrigerant distribution pipe of the prior art, and a requirement for improvement is present.
The present application is made by the inventor based on findings and knowledge about the following facts and problems.
In the related art, the refrigerant distribution pipe is inserted into the header, which may improve uniformity of the refrigerant distribution, but it is found through a great deal of studies and experiments that a dryness, a flow rate and a flow direction of the refrigerant at an inlet of the header, a location of an refrigerant inlet on the header, the number of flat tubes, a depth by which the flat tubes are inserted into the header and other factors have significant influences on the uniform distribution of the refrigerant. Therefore, it is required to determine the refrigerant distribution pipe according to an operating condition of the heat exchanger and after repeated installation, redesign and repeated tests. However, the refrigerant distribution pipe cannot be adjusted accordingly as the operating condition of the heat exchanger varies, so it is impossible to satisfy the refrigerant distribution requirements of the heat exchanger under different operating conditions.